The present process relates to fabrication of articles, either as intermediate or final products, from a zirconium alloy containing, in addition to zirconium, between about 0.5 to 2.0 percent by weight of niobium, up to about 1.5 percent by weight tin, and a minor amount, up to about 0.25 percent by weight of a third element such as iron, chromium, molybdenum, vanadium, copper, nickel and tungsten. The resultant products, produced according to the present invention, have a particular microstructure that enables the material to resist corrosion in high temperature steam environments.
In the development of nuclear reactors, such as pressurized water reactors and boiling water reactors, fuel designs impose significantly increased demands on all of the core components, such as cladding, grids, guide tubes, and the like. Such components are conventionally fabricated from the zirconium-based alloys, Zircaloy-2 and Zircaloy-4. Increased demands on such components will be in the form of longer required residence times and thinner structural members, both of which cause potential corrosion and/or hydriding problems. These increased demands have prompted the development of alloys that have improved corrosion and hydriding resistance, as well as fabricability and mechanical properties that are typical of the conventional Zircaloys. One such class of materials are the zirconium alloys containing zirconium, niobium, tin, and a third element, such as a zirconium alloy containing 1 percent by weight niobium, 1 percent by weight tin, and at least 0.15 percent by weight iron. The only technical limitation which could prevent the utilization of these alloys is that they ordinarily exhibit optimum corrosion and hydriding resistance only after they have been rapidly quenched from high temperatures in the beta-treatment range (.about.850.degree.-950.degree. C.) and then aged for long time periods such as 8-24 hours at about 500.degree.-600.degree. C. This type of treatment cannot readily be applied to any of the required core components, and thus the usefulness of these alloys is severely limited.